as for you question about the game size yest that is normal most games very in size some significantly from others.

If you are using USB loader gx on the main title screen hit "1" on your wiimote and then just DL the covers it will save them to your SD card or your usb Drive if you are running a dual partition on it.

depending on the size of the game... yeah you will only get a few games at most on a 4gig.

either get a bigger usb drive like a "WD passport" or your gonna do alot of running back and forth from your pc to wii just to swap out a game

Title IMages are stored in the "Images" folder on the root of your SD card.. if your using USB loader GX and cant download the images through the wii.. use this site to find your covers and place the .png images in the folder